| 摘要 |
A silicon film 9 and an N+-type impurity region 9a are provided between a base region 11 and an epitaxial growth layer 3. A silicon oxide film 12 is provided on the inner sidewalls of an opening 16, and an N-type polycrystalline silicon film 13 and an emitter region 15 are provided in the region surrounded by the silicon oxide film 12. The silicon film 9 is formed by means of a molecular beam epitaxy and the N-type impurity region 9a is formed prior to the formation of the base region 11 by means of ion implantation that uses a silicon oxide film 7 as the mask. As a result, it is possible to suppress the reduction in the cut-off frequency, and reduce the capacity between the base and the collector, so that a high speed operation of the bipolar transistor becomes possible. |
